CHAPTER VIII.
THE CONTROVERSY ON COMETS.
Seven years passed by, during which Galileo lived a secluded and studious life in the Villa Segni, at Bellosguardo, near Florence, without publishing any new work. How could he do so? The acceptance and further application of the Copernican system was the mainspring of all his scientific pursuits, of which, multifarious as they were, the principle of the double motion of the earth was both foundation and keystone. The general permission to employ the theory as a working hypothesis was of little service to him. The lofty structure of correct knowledge of our universe could not be raised on a pedestal of sand; it required the imperishable marble of truth. Galileo was compelled to withhold the results of his researches until, perchance, some altered state of things should change the mind of the papal court, at present so inimical to the Copernican cause. The publication of any researches in accordance with the Copernican system appeared especially dangerous, until the promised corrections had been made in the famous work of the Canon of Frauenburg, which had been temporarily placed on the Index. These corrections would give more
